In recent years, from the standpoint of environmental stress, reduction of organic solvent usage has been desired. With respect to the pressure-sensitive adhesive (PSA) composition laminated on a PSA sheet, it has been also underway to shift from solvent-based PSA compositions where an organic solvent is used as the solvating media to water-dispersed PSA compositions where water is used as the dispersion media.
As such a PSA, an acrylic PSA has been widely used because of its versatility. However, there exists a problem such that an acrylic PSA, in general, is poorly adhesive to a non-polar adherend such as polyethylene and polypropylene.
In order to solve this kind of problem, in a disclosed method, a tackifying resin having a high softening point is added (e.g., see Patent Document 1). Also disclosed is a PSA that comprises an acrylic polymer and a rubber-based PSA, and further comprises a rosin-based tackifying resin, whereby the PSA exhibits good adhesiveness to a non-polar adherend even at a low temperature (e.g., see Patent Document 2).